Specifications

Excalibur Multirate DAP Installation and Operation
2-10
The Clear Secondary Channel feature is provided during dial backup operation. The only
restriction is that the 600 and 1200 bps channel rates are not available when the Switched
56 IDBU option is installed.
When configured for automatic dialing, the DAP places the required telephone call in
response to one of the following user-selectable conditions:
• DDS Down - DDS goes down due to Out of Service codes, Abnormal Station
codes, loss of multiport framing, or loss of network framing for a user-selectable
time period.
• No Signal - an invalid DDS signal is received from the network.
• Network Down - the DAP dials after the DDS network goes down or an invalid
signal is received from the network.
• DTR - the DAP dials when the DTR signal is active. This setting allows external
routers and FRADs to originate dial backup calls.
Note: The DAP will not automatically dial when it is in a test state such as End-to-End
Network Loops.
You may select any DAP in the network (remote or central) for automatic dialing. Both
DAPs can answer a call, but only one should be configured to automatically originate the
call.
When a dial backup connection is initiated (through any of the methods), the following
events occur:
1. The originating DAP goes off-hook. When it detects a wink (dial tone) from the
network, it dials the previously stored primary telephone number of the
answering DAP.
2. The answering DAP detects the incoming call as a line seizure (off-hook state)
from the network. After determining that the line seizure was not a line hit, the
answering DAP goes off-hook to signal the network that it has answered the call.
3. The network presents a line seizure to the originating DAP to signal that the
answering DAP has answered the call.
4. The data path is now complete and both DAPs switch over to the dial line.
Front Panel Status Information
The following status information is displayed on the front panel while the dial-up
connection is being established (through any of the methods):
• A dial backup connection is being established.